Bring all ingredients except collard greens to boil in a large saucepan; reduce heat to medium; simmer until onion has softened and flavors have come together (about 15 minutes); add greens; bring to a boil; reduce heat to medium; simmer until softened (about 4 minutes); remove from heat; reserve (keep warm).

Assembly:

1 cup cornmeal

1 cup all-purpose flour

1/2 Tbsp. salt

1 tsp. black pepper, freshly ground

4 2"-squared catfish fillets

peanut oil (for frying)

Whisk cornmeal and flour in shallow bowl; season catfish with salt and pepper; dredge in cornmeal mixture; reserve.

Heat large cast-iron skillet set over medium-high heat; add oil to fill about 1/4" up sides of pan; working in batches, fry catfish, turning halfway through, until brown and crispy; place on paper towels to drain; reserve (keep warm).

To serve, add catfish to broth; bring to a boil; cook 5 to 6 minutes; divide fish, greens, and broth among bowls.